The United States military said on Thursday it has killed 24 al-Shabaab extremists with an airstrike in Somalia, one of its deadliest in months.The airstrike was carried out on Wednesday near an extremist camp near Shebeeley in the central Hiran region north of the capital, Mogadishu, the US Africa Command said in a statement.It was the ninth such airstrike carried out by the US this year. The US carried out nearly 50 strikes last year in the Horn of Africa nation against the al-Qaeda-linked al-Shabaab, the deadliest Islamic extremist group in Africa.Al-Shabaab has claimed responsibility for the attack on a hotel complex in the capital of neighbouring Kenya earlier this month that left 21 people dead. The extremist group, which targets Kenya in retaliation for sending troops to Somalia, has also targeted hotels, government offices and checkpoints in Mogadishu with suicide bombings.The group is also accused of stealing humanitarian aid in the often drought-hit country and extorting residents and travelers to fund its attacks.The US statement said the airstrikes are meant to support Somali forces as they increase pressure on al-Shabaab and its recruiting efforts in the region, especially in southern and central Somalia. Extremist camps and other safe havens are targeted.The US statement said no civilians were killed or injured in the latest airstrike.On January 19 the US said an airstrike had killed 52 al-Shabaab extremists in Middle Juba region after a "large group" mounted an attack on Somali forces. A Somali intelligence officer said the extremist group had been amassing some 400 fighters for more than a week to launch a major attack against Somali and Kenyan forces in order to disrupt a planned offensive.In October, the US said an airstrike killed about 60 fighters near the al-Shabaab-controlled community of Harardere in Mudug province in the central part of the country.The United States has dramatically stepped up airstrikes against al-Shabaab in Somalia since President Donald Trump took office. Experts have said it will take more than airstrikes, however, to defeat the extremists.Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and Facebook.